Help me understand why OpenID is worth paying attention to. Smart, respectable alpha-geek Simon Willison has focused on pretty much nothing else for the past few weeks, but I can't picture why this is an interesting or desirable technology. It's being touted as an example of "light-weight identity", an adjective I don't think should be applied to any proposed standard suggesting an entirelynewkind of identifier. I'm still having trouble with the difference between URL and URI, so what is an XRI for? The protocol may be "drop dead simple", but this sounds like a deal-breaker for any non-wizard looking to understand how it works:

Now, in practice there will probably be concerns about spoofing, so Consuming sites will have whitelists, and which is why you may need multiple Providers to ensure they have one that works everywhere they need it.

My gut feeling is that OpenID is this year's architecture aeronautics moon shot. This ZDNet article makes the case for OpenID, but it lists only three proposed benefits for the "internet user", the only actor whose opinion actually matters in the long haul. Personally, all of the suggested OpenID uses (starting with: "I don't want to remember a long list of usernames and passwords for every site I visit") I've seen are already handled elegantly by KeyChain, Mac OSX's client-side password and secret storage program. "Identity" is itself a fairly abstract concept - I suspect that most people think of it in concrete terms, using wallet-compatible tokens like their drivers license or gym membership card as stand-ins. For internet stuff, my token is my laptop, under my personal control at all times with copies of all those usernames and passwords. If the iPhone spurs US carriers to open up WiFi or bluetooth on phones, my token might be my cell phone. Either way, it's going to stay a physical object with predictable real-world properties.